Is it better to choose a lead-acid battery for an electric bike, or a lithium battery that is more powerful? If the lead-acid battery is good, why not choose it for this model? After figuring this point, there is nothing to entangle. The answer is definitely that lead-acid batteries are worse, regardless of safety, stability or durability.
If there is any advantage of the battery, it is that the manufacturing cost is lower, but it is also limited to the comparison of ordinary ternary lithium, if it is faced with lithium iron phosphate, it will inevitably be much worse.
Lead-acid battery characteristics
All batteries or batteries are called "chemical power sources." Charging and discharging are based on chemical reactions. Electric current is only a result, not a prerequisite. The lead-acid battery immerses both the positive and negative plates in the electrolyte. The electrolyte uses [sulfuric acid solution], and the positive and negative electrodes are lead and lead dioxide.
The charging process uses 220V electricity from the grid to input current to the positive electrode; the current catalyzes the reaction of divalent lead ions with the charged sulfate radicals of the electrolyte and decomposes into lead to increase the concentration of the solution. To put it bluntly, it means to "dissolve" the lead sulfate crystals on the plates, which is the purpose of charging.
"Discharge" is a directional reaction. The discharge sulfuric acid of the electrolyte will react with the active material of the electrode plate, and an electric current will be generated in the process; but at the same time, lead sulfate crystals will also be generated and will adhere to the electrode plate.
Most of the crystals are decomposed again during charging, but some high-hardness crystals are left after each charge and cannot be effectively reduced; this is the so-called "plate vulcanization", and the stubborn existence will cause a linear decrease in the concentration of the electrolyte. Because of the fact that the reducible lead is reduced. At the same time, these substances will affect the reaction efficiency of the active material. The increase in the discharge capacity is equivalent to the reduction of the capacity again, so the cruising range will become lower and lower.
Key point: Because each charge and discharge will cause the attenuation of the active material and increase the degree of vulcanization; therefore, the service life of a lead-acid battery is very short, generally it will be scrapped if it is fully charged and discharged less than 400 times.
However, the electric bicycle is small in size but the battery energy density is very low* (large volume), and the vehicle cannot be equipped with enough batteries. As a result, the capacity is also low enough. If you ride every day, it will be scrapped in almost a year. The cost of replacing a set can range from a few hundred yuan to thousands of yuan. Is the potential cost of using a car quite high?
Ordinary ternary lithium
NCM·Ni-Co-Mn ternary lithium battery has been used in the early days. This kind of battery is characterized by high manufacturing cost. The average electricity consumption is about 1.5k per kilowatt-hour, which is almost twice as high as that of lead-acid batteries. Therefore, in early Internet electric bicycle brands such as Mavericks, the price of vehicles is always quite high, which creates a prejudice that lithium batteries are more expensive.
Moreover, the safety level of this kind of battery is not very high, because the energy density is too high. If the stability of the control system is poor during charging and discharging, the battery is indeed prone to high temperature or even fire. Therefore, the initial evaluation of lithium battery electric bicycles is very poor.
Key point: The advantage of this type of ternary lithium is actually "high energy density." A lithium battery of the same volume or quality will surely store electricity 3 to 5 times higher than that of a lead-acid battery. That is to say, the same battery pack uses lithium batteries, and the cruising range can be increased exponentially; but because of the high cost, it is impossible to equip too many batteries, so the actual cruising range is up to 1 to 2 times.
Therefore, users who have high endurance requirements will always choose this kind of battery, as long as it is a regular electric bicycle brand vehicle, it is actually safe enough.
Excellent lithium iron battery
LFP·LiFePO4 battery should be the best option for three reasons. High safety, high durability, and high energy density.
Excellent iron batteries (for automobiles) have undergone very strict tests. For example, the blade-type iron batteries introduced by BYD. In the tests of short circuit, overcharge and furnace temperature, the battery not only did not catch fire, but the temperature standard was not enough to fry eggs. The reason is that the composite material of the plate is not "lively", and iron is the most stable element in the universe; for example, after a yellow dwarf star has undergone countless fusion reactions, the supermassive star that is finally formed is an "iron ball". What a good response.
Then after there are no more concerns about safety, the service life of this battery can be dozens of times that of lead-acid; relying on the insertion and deintercalation of the positive and negative electrodes of lithium ions, the particularity of the electrolyte will not cause "sulfide". , So the service life can be very high. And the energy density is still 3 to 4 times that of the battery, and the cruising range is guaranteed.
The most important thing: the manufacturing cost of lithium iron phosphate batteries can be very low, as low as more than 200 yuan can have one kilowatt-hour of electricity, it seems that the battery is not so cheap. Therefore, as long as the installed capacity of iron-lithium batteries can grow rapidly, and more and more companies invest in iron-lithium R&D and production, the price of lithium-ion electric bicycles will eventually be lower and the overall quality of the vehicles will be higher and higher.
Moreover, this kind of battery has the value of cascading utilization. After the vehicle is eliminated, most of the batteries can be sorted out and sent to the energy storage station to accelerate the growth of new energy power generation. By then, electric bicycles will also belong to new energy models, and there will be nothing to use cars. Limit it.
The topic of electric bicycle batteries is here, and the choice of car should be the iron-lithium battery as the first choice.
